<!DOCTYPE html>
<html lang="en">
<head>
    <meta charset="utf-8">
    <title>作业二</title>
</head>
<body>
 
    <script>
        var str = prompt("请输入英文单词：");
        // document.write(str.substring(0,1));
        document.write(str.substring(0,1).toUpperCase()+str.substring(1));
   
    </script>
    

</body>
</html>